For some years the Principal Investigator (PI) has collaborated with Dr. Magrath's laboratory and with a number of investigators in different parts of the world. The collaboration has focused (1) on the molecular characterization of lymphoid neoplasia in developing countries, and (2) on providing appropriate treatment, including supportive care, in such settings. All of these investigators are to be brought together September 4-6, 1990, for an international workshop in Bethesda to share data and experiences. The workshop will deal mostly with acute lymphoblastic leukemia and with non-Hodgkins lymphomas, including those associated with HIV infection. The workshop will be preceded and followed by hands-on laboratory sessions dealing with DNA extraction from tumor samples and characterization of chromosomal breakpoint translocations and EBv association. These sessions will take place in Dr. Ian Magrath's laboratory in the Clinical Center, NIH. Each of the 26 non-NCI participants will spend on the average seven days on the NIH campus. The application requests per diem and block travel support to cover the expenses of the non-NCI participants.